関連ワード:  when to use et al in references    when to use et al in references apa    when to use et al in references apa 7    when to put et al in references    when to use et al in referencing    when to use et al in reference list    when to use et al in reference list apa    when to use et al in reference list harvard    when to use et al in reference list apa 7    when to use et al in referencing harvard